For a Travel agency application

$1.$ Create the use$-$case model diagrams for three subjects User Registration, flight booking and payment processing

$2.$ Create use$-$case descriptions for at least two of the use cases you are using in your usecase models. The use cases will comprise the following components:

Use case title

Brief description

Flow of events $($this is a detailed diagram capturing the internal flows for the use case$)$

Special requirements

Precondition

Postconditions

Extensions

Relationships

$3.$ Start creating an object$-$oriented $($OO$)$ class diagram for your system using a tool of your choice. The OO class diagram will include key attributes $($data$-$items$),$ operations $($behaviors$),$ and any generalization relationships between classes you would like to highlight.